[Three cases of IgG4-related focal retroperitoneal fibrosis].

(Case 1) A 63-year-old man was diagnosed as retroperitoneal fibrosis by the exploratory laparotomy for the pelvic mass with high IgG4 levels. (Case 2) A 64-year-old man had past medical history of autoimmune pancreatitis which was treated by steroid use. Three years later, he was diagnosed as IgG4-related gallbladder tumor by the cholecystectomy. And, then he was diagnosed as right hydronephrosis with high IgG4 levels. (Case 3) A 71-year-old man was diagnosed as left hydronephrosis and pelvic mass by computerized tomography with high IgG4 levels. We reported three cases of IgG4-related focal retroperitoneal fibrosis. All cases had pelvic mass with high IgG4 levels and were also treated effectively with steroid use. Those symptoms of the patients occurred in close association with IgG4 levels. It is necessary to acknowledge that retroperitoneal fibrosis may have aspects of IgG4-related systemic disease and that the measurement of serum IgG4 should be considered for diagnosing and treating the conditions.